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ABSTRACT Most efforts to detect signatures of dynamical dark energy (DE) are focused on late times, z ≲ 2, where the DE component begins to dominate the cosmic energy density. Many theoretical models involving dynamical DE exhibit a ‘freezing’ equation of state however, where w → −1 at late times, with a transition to a ‘tracking’ behaviour at earlier times (with w ≫ −1 at sufficiently high redshift). In this paper, we study whether constraints on background distance indicators from large-scale structure (LSS) surveys in the post-reionization matter-dominated regime, 2 ≲ z ≲ 6, are sensitive to this behaviour, on the basis that the DE component should remain detectable (despite being strongly subdominant) in this redshift range given sufficiently precise observations. Using phenomenological models inspired by parameter space studies of Horndeski (generalized scalar-tensor) theories, we show how existing CMB and LSS measurements constrain the DE equation of state in the matter-dominated era, and examine how forthcoming galaxy surveys and 21 cm intensity mapping instruments can improve constraints in this regime at the background level. We also find that the combination of existing CMB and LSS constraints with DESI will already come close to offering the best possible constraints on H0 using BAO/galaxy power spectrum measurements, and that either a spectroscopic follow-up of the LSST galaxy sample (e.g. MegaMapper or SpecTel) or a Stage 2/PUMA-like intensity mapping survey, both at z ≳ 2, would offer better constraints on the class of models considered here than a comparable cosmic variance-limited galaxy survey at z ≲ 1.5.
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An algorithm to locate the centers of baryon acoustic oscillations
Context. The cosmic structure formed from baryon acoustic oscillations (BAO) in the early universe is imprinted in the galaxy distribution observable in large-scale surveys and is used as a standard ruler in contemporary cosmology. Typically, BAOs are detected as a preferential length scale in two-point statistics, which gives little information about the location of the BAO structures in real space. Aims. The aim of the algorithm described in this paper is to find probable centers of BAOs in the cosmic matter distribution. Methods. The algorithm convolves the three-dimensional distribution of matter density with a spherical shell kernel of variable radius placed at different locations. The locations that correspond to the highest values of the convolution correspond to the probable centers of BAOs. This method is realized in an open-source, computationally efficient algorithm. Results. We describe the algorithm and present the results of applying it to the SDSS DR9 CMASS survey and associated mock catalogs. Conclusions. A detailed performance study demonstrates the ability of the algorithm to locate BAO centers and in doing so presents a novel detection of the BAO scale in galaxy surveys.
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- Award ID(s):
- 1757062
- PAR ID:
- 10319871
- Date Published:
- Journal Name:
- Astronomy & Astrophysics
- Volume:
- 647
- ISSN:
- 0004-6361
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1051/0004-6361/202039257
